Process for the production of enantiomer-enriched alpha-substituted carboxylic acids

ABSTRACT

The present invention provides enzymatic processes for the production of enantiomer-enriched u-substituted carboxylic acids.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to German Application No. DE 101 15 000.8, filed on Mar. 26, 2001, which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to enzymatic processes for the production of enantiomer-enriched α-substituted carboxylic acids.

[0004] 2. Discussion of the Background

[0005] In organic synthesis, α-substituted carboxylic acids serve as important intermediates for the production of several classes of compounds. However, the synthesis of some of these classes, such as amino acids and diols, require the α-substituted carboxylic acids to be present to a high optical purity, particularly when the α-substituted carboxylic acid is to be used for the production of bioactive substances or catalysts.

[0006] One such process is described in WO0058449 (and references cited therein), which describes an enzymatic reaction of hydantoins to yield enantiomer-enriched amino acids. However, processes for the complete conversion of hydantoin analogues to optically enriched α-substituted carboxylic acids are not known. Therefore, there is a critical need for methods of producing enantiomer-enriched populations of α-substituted carboxylic acids from racemic mixtures of hydantoin analogues.

[0007] α-Substituted carboxylic acids, which constitute the subject matter of the present invention may be obtained by processes known in the art. For example, the optical antipodes of the compounds under consideration may be obtained by conventional racemate resolution of the racemic mixtures or by chromatographing them on chiral phases. The racemic mixtures themselves are sometimes cheap compounds, while some enantiomers of the α-substituted carboxylic acids may also be obtained from the chiral pool.

SUMMARY OF THE INVENTION

[0008] Therefore, it is an object of the present invention to provide a process for the production of enantiomer-enriched α-substituted carboxylic acids.

[0009] Another object of the present invention is to provide a process capable of providing a wide range of compounds at the highest possible optical purities and at the lowest possible cost. Further, it is an object of the present invention to provide such a process that is industrially robust.

[0010] Another object of the present invention is a process for the production of enantiomer enriched α-substituted carboxylic acids by transforming compounds of formula (I)

[0011] wherein, X is O, S, or CH₂, and R is an enzyme-reactive organic residue with enzymatic ring cleavage by a hydantoinase to form intermediate product of formula (II);

[0012] wherein, X is O, S, CH₂, and R is an enzyme-reactive organic residue. Subsequently, the compound of formula (II) is converted by a carbamoylase to yield the desired enantiomer-enriched α-substituted carboxylic acid.

[0013] In another object of the present invention a process is provided in which enantiomer-enriched α-substituted carboxylic acids are produced by a reaction with a carbamoylase with compounds of formula (II)

[0014] wherein X is O, S, or CH₂, and R is an enzyme-reactive organic residue.

[0015] Another object of the present invention is to provide a process in which a racemase is also used in addition to a hydantoinase and/or a carbamoylase to yield enantiomer-enriched α-substituted carboxylic acids.

[0016] Another object of the invention relates to the use of the enantiomer-enriched α-substituted carboxylic acids as a substrate in organic synthesis, inter alia for the synthesis of catalysts, or for the production of bioactive compounds.

[0017] The above objects highlight certain aspects of the invention. Additional objects, aspects and embodiments of the invention are found in the following detailed description of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0018] Unless specifically defined, all technical and scientific terms used herein have the same meaning as commonly understood by a skilled artisan in biochemistry, cellular biology, and organic chemistry.

[0019] All methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, with suitable methods and materials being described herein. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. Further, the materials, methods, and examples are illustrative only and are not intended to be limiting, unless otherwise specified.

[0020] Enantiomer-enriched α-substituted carboxylic acids according to the invention are important intermediates for organic synthesis, but they may also be used to obtain a range of other important optically highly pure classes of compounds, such as amino acids, diols etc., which may be used in organic synthesis for the production of bioactive substances or as catalysts.

[0021] In the process for the production of enantiomer-enriched α-substituted carboxylic acids by transforming compounds of formula (I)

[0022] wherein, X is O, S, or CH₂, and R is an enzyme-reactive organic residue reacts with enzymatic ring cleavage by a hydantoinase to form intermediate product of formula (II)

[0023] wherein, X is O, S, or CH₂, and R is an enzyme-reactive organic residue reacts. Subsequently, the intermediate of formula (II) is converted by a carbamoylase to yield the desired enantiomer-enriched α-substituted carboxylic acid.

[0024] In another embodiment, the process involves producing enantiomer-enriched α-substituted carboxylic acids by a reaction with a carbamoylase and compounds of formula (II)

[0025] wherein X is O, S, or CH₂, and R is an enzyme-reactive organic residue.

[0026] “Optically enriched” or “enantiomer-enriched” compounds within the scope of the present invention is understood to mean the presence of an optical antipode mixed with the other antipodes in a concentration of >50 mole %. Further, within the scope of the present invention are compounds that relate to both D- and L- optical isomers.

[0027] In principal, suitable R groups may be any organic residue that permits reaction of the compounds of the formulae (I) or (II) in the enzyme systems of the present invention. The determination of suitable R groups is readily ascertainable by the skilled artisan through routine experimentation. Preferred R groups for use in the present invention include (C₁-C₈)-alkyl, (C₁-C₈)-alkoxy, (C₂-C₈)-alkoxyalkyl, (C₆-C₁₈)-aryl, (C₇-C₁₉)-aralkyl, (C₃-C₁₈)-heteroaryl, (C₄-C₁₉)-heteroaralkyl, (C₁-C₈)-alkyl-(C₆-C₁₈)-aryl, (C₁-C₈)-alkyl-(C₃-C₁₈)-heteroaryl, (C₃-C₈)-cycloalkyl, (C₁-C₈)-alkyl-(C₃-C₈)-cycloalkyl, (C₃-C₈)-cycloalkyl-(C₁-C₈)-alkyl, (C₁-C₈)-acyl, and (C₁-C₈)-acyloxy. More preferred R groups may be those which match the corresponding α-residues of proteinogenic or natural amino acids. However, the R group may correspond to the α-residues of non-proteinogenic or unnatural amino acids. Natural (or proteinogenic) α-amino acids are described in Bayer-Walter, Lehrbuch der organischen Chemie, S. Hirzel Verlag, Stuttgart, 22nd edition, 1991, pp. 822 et seq.. Furthermore, preferred examples of unnatural or non-proteinogenic α-amino acids are described in DE 19903268.8. In addition, the side chain residues may be derived from the α-amino acids presented therein.

[0028] (C₁-C₈)-Alkyl groups should be taken to mean methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl or octyl, including all bond isomers thereof. The (C₁-C₈)-alkoxy group corresponds to a (C₁-C₈)-alkyl group with the proviso that the latter is attached to the molecule via an oxygen atom. (C₂-C₈)-Alkoxyalkyl is intended to mean groups in which the alkyl chain is interrupted by at least one oxygen function, where two oxygen atoms may not be joined together. The number of carbon atoms indicates the total number of carbon atoms present in the substituent group.

[0029] The aforementioned substituents may be mono- or polysubstituted with halogens and/or residues containing N, O, P, S or Si atoms. These are in particular alkyl residues of the above-stated type which contain one or more of these heteroatoms in their chain or which are attached to the molecule via one of these heteroatoms.

[0030] (C₃-C₈)-Cycloalkyl is a cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or cycloheptyl residues etc.. These may be substituted with one or more halogens and/or residues containing N, O, P, S, Si atoms and/or comprise N, O, P, S atoms in the ring, for example 1-,2-,3-,4-piperidyl, 1-,2-,3-pyrrolidinyl, 2-,3-tetrahydrofuryl, 2-,3-,4-morpholinyl.

[0031] A (C₃-C₈)-cycloalkyl-(C₁-C₈)-alkyl designates a cycloalkyl residue as described above which is attached to the molecule via an alkyl residue as stated above.

[0032] For the purposes of the invention, (C₁-C₈)-acyloxy means an alkyl residue having at most 8 C atoms as described above which is attached to the molecule via a COO function.

[0033] For the purposes of the invention, (C₁-C₈)-acyl means an alkyl residue having at most 8 C atoms as described above which is attached to the molecule via a CO function.

[0034] A (C₆-C₁₈)-aryl residue is an aromatic residue having 6 to 18 C atoms. In particular, these compounds include those such as phenyl, naphthyl, anthryl, phenanthryl, biphenyl residues or systems of the above-described type fused to the molecule in question, such as indenyl systems, which may optionally be substituted with (C-C₈)-alkyl, (C₁-C₈)-alkoxy, N(C₁-C₈)-alkyl, (C₁-C₈)-acyl, (C₁-C₈)-acyloxy.

[0035] A (C₇-C₁₉)-aralkyl residue is a (C₁-C₈)-aryl residue attached to the molecule via a (C₆-C₁₈)-alkyl residue.

[0036] For the purposes of the invention, a (C₃-C₁₈)-heteroaryl residue means a five-, six- or seven-membered aromatic ring system comprising 3 to 18 C atoms which comprises heteroatoms, such as nitrogen, oxygen or sulfur in the ring. Such heteroaromatic compounds are in particular taken to be residues such as 1-,2-,3-furyl, such as 1-,2-,3-pyrrolyl, 1-,2-,3-thienyl, 2-,3-,4-pyridyl, 2-,3-,4-,5-,6-,7-indolyl, 3-,4-,5-pyrazolyl, 2-,4-,5- 5 imidazolyl, acridinyl, quinolinyl, phenanthridinyl, 2-,4-, 5-,6-pyrimidinyl.

[0037] A (C₄-C₁₉)-heteroalkyl is a heteroaromatic system corresponding to the (C₇-C₁₉)-aralkyl residue.

[0038] Suitable halogens (Hal) which may be employed in the above substituent groups are fluorine, chlorine, bromine and iodine.

[0039] In the process of the present invention, a racemase may also be used to yield enantiomer-enriched α-substituted carboxylic acids.

[0040] In this process, the racemase is contacted with compounds (I) and/or (II) is treated with a racemase. As shown in Scheme (I), a consequence of this treatment is that a racemic starting product may almost completely give rise to an enantiomer of the α-substituted carboxylic acids according to the present invention.

[0041] In another embodiment of the invention, racemisation proceed by other means, in particular by chemical processes may be employed. Suitable racemisation processes and racemases are described, for example, in EP0542098, DE10050124.9, DE10050123.0, DE19935268 and DE19529211.1. Preferred racemases for use in the present invention include a hydantoin racemase, a carbamoylamino acid racemase, a or N-acetylamino acid racemase.

[0042] A preferred embodiment of the present invention is a process in which the enzymes used are provided in recombinant manner by expression from host organisms (thesis by Martin Hils: Mutanten der D-Carbamoylase zur Bildung aktiven Enzyms bei Expression des Gens in Escherichia coli and Analyse eines Genclusters fur die Enzyme des Hydantoin-Abbaus aus Agrobacterium sp IP I-671; Verlag Ulrich E. Grauer, Stuttgart 1998). Accordingly, the reaction may be performed with the assistance of a host organism, which is capable of expressing the appropriate enzymes. Preferably, all the enzymes to be used to achieve this object are expressed by a single host organism (whole cell catalyst WO0058449).

[0043] The form of the host organism expressing the hydantoinase, carbamoylase, and/or racemase to be used in the reactions of the present invention is not particularly limiting. For example, the host organism may be undisrupted, partially disrupted, or entirely disrupted. Further, the host organism may be used solely as an expression source from which the aforementioned enzymes may be purified to virtual homogeneity. The essentially homogenous enzymes may then be used to achieve the objects of the present invention.

[0044] Examples of host organisms suitable for use with the present invention include the E. coli strains NM 522, JM109, RR1, DH5α, TOP 10, and HB101.

[0045] In principle, any enzymes which may be considered by the person skilled in the art for the purpose according to the invention may be used for the reaction. Descriptions of the preferable hydantoinase, carbamoylase, and racemase enzymes for use in the present invention may be found in “Enzyme Catalysis in Organic Synthesis”, (eds.: Drauz, Waldmann, VCH, 1^(st) ed., 1995).

[0046] Hydantoinases from the organism Bacillus sp., Agrobacterium sp. or Arthrobacter sp. are preferable to achieve the objects of the present invention. A preferred hydantoinase is the commercially available hydantoinase 1 from Roche Diagnostics GmbH or the hydantoinase from Arthrobacter aurescens DSM3747 (SEQ ID NO: 4) or Arthrobacter aurescens DSM3745 (SEQ ID NO: 3). A preferred source of the hydantoinase is Bacillus thermoglucosidasius.

[0047] The carbamoylase to be used in the present invention may be obtained from Agrobacterium radiobacter IP I-671 (SEQ ID NO: 1) or Arthrobacter crystallopoietes DSM 20117 (SEQ ID NO: 2) are preferably used as the carbamoylase. Agrobacterium radiobacter IP 1-671 and Arthrobacter crystallopoietes DSM 20117 are commercially available.

[0048] Preferable racemases for use in the present invention include a hydantoin racemase, a carbamoylamino acid racemase, or a N-acetylamino acid racemase (DE1 0050124.9, DE10050123.0, U.S. Ser. No. 09/407062, WO0058449).

[0049] In one embodiment of the present invention, the reaction is preferably performed in an enzyme membrane reactor (DE 199 10 691.6).

[0050] The present invention also provides a use of the enantiomer-enriched α-substituted carboxylic acids as a substrate in organic synthesis, inter alia for the synthesis of catalysts, or for the production of bioactive compounds.

[0051] The compounds of the formula (I) to be used in the reaction according to the invention may be produced using methods known in the art. The oxa- or thia- analogous hydantoin structures may accordingly be obtained from the corresponding racemic α-hydroxy or α-mercaptocarboxylic acids by reaction with phosgene or methoxy- or benzyloxycarbonyl chloride (by analogy with H. Leuchs. Ber. 39, 857 (1906)). An alternative method which could be employed is the condensation of 2,4-dioxothiazolidines or 2,4-dioxooxazolidines with aldehydes and subsequent reduction of the double bond by analogy with hydantoin syntheses (Beyer-Walter, Lehrbuch der organischen Chemie, S. Hirzel Verlag, Stuttgart, 22nd edition, 1991, p. 744). An additional overview of suitable methods of producing compounds of formula (I) are provided in the thesis by T. Waniek (University of Stuttgart 1999).

[0052] As previously stated, the enzymes of the present invention may be used together or in succession. Additionally, these enzymes may be in free form as homogeneously purified compounds or as enzymes produced by recombinant means. Further, the enzymes may also be used as a constituent of a guest organism (whole cell catalyst as in U.S. Ser. No. 09/407062, WO0058449) or in conjunction with the disrupted cell mass of the host organism. It may also be possible to use the enzymes in an immobilised form (Bhavender P. Sharma, Lorraine F. Bailey and Ralph A. Messing, “Immobilisierte Biomaterialiem—Techniken and Anwendungen”, Angew. Chem. 1982, 94, 836-852).

[0053] Enzyme immobilisation may be achieved, for example, by freeze-drying (Dordick et al. J. Am. Chem. Soc. 1994, 116, 5009-5010; Okahata et al. Tetrahedron Lett. 1997, 38, 1971-1974; Adlercreutz et al. Biocatalysis 1992, 6, 291-305). In a preferred method, freeze-drying is performed in the presence of surface-active substances, such as Aerosol OT, polyvinylpyrrolidone, polyethylene glycol (PEG), or Brij 52 (diethylene glycol monocetyl ether; Goto et al., Biotechnol. Techniques 1997, 11, 375-378).

[0054] Having generally described this invention, a further understanding can be obtained by reference to certain specific examples, which are provided herein for purposes of illustration only, and are not intended to be limiting unless otherwise specified.

EXAMPLES Example 1

[0055] Regio- and enantio-specific hydrolysis of BnBHA with D-carbamoylases (hydantoinase reaction, c.f. thesis of T. Waniek, Stuttgart 1999).

[0056] A mixture of D,L-2-BnBHA and D,L-3-BnBHA (44:56, HPLC) was dissolved at a concentration of 2 g/l (9.6 mM) in 200 μl of 0.1 M potassium phosphate buffer, pH 7.0, and combined with 80 μl of enzyme solution. Incubation was performed in a Thermomixer at 37° C. for the D-carbamoylase from Agrobacterium radiobacter IP I-671 and at 30° C. for the D-carbamoylase from Arthrobacter crystallopoietes DSM 20117. The reaction was terminated by combining 280 μl of reaction solution with 100 μl of 10% phosphoric acid. The reaction batch was centrifuged and the supernatant diluted 1:10 with HPLC mobile solvent and analysed.

[0057] After a reaction time of 10 min, RP₁₈HPLC revealed 3-BnBHA conversion of 50%, while 2-BnBHA was not converted.

[0058] Chiral HPLC analysis (cyclodextrin phase) revealed that the resultant D-BnBS was enantiomerically pure.

[0059] Specific enzyme activity was determined at least 3.2 U/mg.

Example 2

[0060] Enantio-specific hydrolysis of CPhM with a D-carbamoylase (hydantoinase reaction, c.f. thesis of T. Waniek, Stuttgart, 1999).

[0061] The substrates were tested both with the D-carbamoylase from Agrobacterium sp. IP I-671 and with that from Arthrobacter crystallopoietes DSM 20117. Where the reaction conditions with the D-carbamoylase vary for Arthrobacter, the different values are given in brackets.

[0062] The D,L-CPhM was dissolved at a concentration of 2 g/l in 400 gl of 0.1 M potassium phosphate buffer, pH 7.0, and combined with 200 μl of enzyme solution. Incubation was performed in a Thermomixer at 37° C. (30° C.). The reaction was terminated by combining 600 μl of reaction solution with 200 μl of 10% phosphoric acid. The reaction batch was centrifuged and the supernatant diluted 1:10 with HPLC mobile solvent and analysed.

[0063] After a reaction time of 60 min (10 min), RP₁₈ HPLC revealed conversion of 33% (2.8%).

[0064] Chiral HPLC analysis (cyclodextrin phase) revealed that only D-PhM had been obtained as the product of the enzymatic reaction.

[0065] Specific enzyme activity was determined at 0.2 U/mg (0.05 U/mg).

Example 3

[0066] Single-Vessel Reaction

[0067] D,L-BOD was dissolved at a concentration of 2 g/l in 1 ml of 0.1 M potassium phosphate buffer, pH 7.0, and combined with 200 μl of L-hydantoinase from Arthrobacter aurescens DSM 3747 immobilised on Eupergit and with 200 μl of D-carbamoylase solution (Agrobacterium sp. IP I-671). Incubation was performed in a Thermomixer at 37° C. The reaction was terminated by combining the immobilisate with 200 μl of 10% phosphoric acid, centrifuging the mixture and diluting the supernatant 1:10 in HPLC mobile solvent and performing analysis.

[0068] After a reaction time of 24 h, RP₁₈ HPLC revealed that both CPhM (˜20%) and PhM (˜5%) had been obtained.

[0069] Numerous modifications and variations on the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the accompanying claims, the invention may be practiced otherwise than as specifically described herein.

1 4 1 304 PRT Agrobacterium radiobacter 1 Met Thr Arg Gln Met Ile Leu Ala Val Gly Gln Gln Gly Pro Ile Ala 1 5 10 15 Arg Ala Glu Thr Arg Glu Gln Val Ile Ala Arg Leu Leu Asp Met Leu 20 25 30 Ala Asn Ala Ala Ser Arg Gly Val Asn Phe Ile Val Phe Pro Glu Leu 35 40 45 Ala Val Thr Thr Phe Phe Pro Arg Trp His Leu Thr Asp Glu Ala Glu 50 55 60 Leu Asp Ser Phe Tyr Glu Thr Glu Met Pro Gly Pro Leu Thr Arg Pro 65 70 75 80 Leu Phe Glu Lys Ala Ala Glu Leu Gly Ile Gly Phe Asn Phe Gly Tyr 85 90 95 Ala Glu Leu Val Val Glu Gly Gly Val Lys Arg Arg Phe Asn Thr Ser 100 105 110 Ile Leu Val Asp Arg Ser Gly Lys Ile Ile Gly Lys Tyr Arg Lys Val 115 120 125 His Leu Pro Gly His Lys Glu Tyr Glu Ala Tyr Arg Pro Phe Gln His 130 135 140 Leu Glu Lys Arg Tyr Phe Glu Pro Gly Asp Met Gly Phe Pro Val Tyr 145 150 155 160 Asp Val Asp Ala Ala Lys Met Gly Met Phe Ile Cys Asn Asp Arg Arg 165 170 175 Trp Pro Glu Ala Trp Arg Val Met Gly Leu Lys Gly Ala Glu Ile Ile 180 185 190 Cys Gly Gly Tyr Asn Thr Pro Thr His Asn Pro Ala Val Pro Gln His 195 200 205 Asp His Leu Thr Ser Phe His His Leu Leu Ser Met Gln Ala Gly Ser 210 215 220 Tyr Gln Asn Gly Ala Trp Ser Ala Ala Ala Gly Lys Val Gly Met Glu 225 230 235 240 Glu Gly Cys Met Leu Leu Gly His Ser Cys Ile Val Ala Pro Thr Gly 245 250 255 Glu Ile Val Ala Leu Thr Thr Thr Leu Glu Asp Glu Val Ile Thr Ala 260 265 270 Thr Ile Asp Leu Asp Arg Cys Arg Glu Leu Arg Glu His Ile Phe Asn 275 280 285 Phe Lys Ala His Arg Gln Pro Gln His Tyr Gly Leu Ile Ala Glu Leu 290 295 300 2 315 PRT Arthrobacter crystallopoietes 2 Leu Ala Lys Asn Leu Met Leu Ala Val Ala Gln Val Gly Gly Ile Asp 1 5 10 15 Ser Ser Glu Ser Arg Pro Glu Val Val Ala Arg Leu Ile Ala Leu Leu 20 25 30 Glu Glu Ala Ala Ser Gln Gly Ala Glu Leu Val Val Phe Pro Glu Leu 35 40 45 Thr Leu Thr Thr Phe Phe Pro Arg Thr Trp Phe Glu Glu Gly Asp Phe 50 55 60 Glu Glu Tyr Phe Asp Lys Ser Met Pro Asn Asp Asp Val Ala Pro Leu 65 70 75 80 Phe Glu Arg Ala Lys Asp Leu Gly Val Gly Phe Tyr Leu Gly Tyr Ala 85 90 95 Glu Leu Thr Ser Asp Glu Lys Arg Tyr Asn Thr Ser Ile Leu Val Asn 100 105 110 Lys His Gly Asp Ile Val Gly Lys Tyr Arg Lys Met His Leu Pro Gly 115 120 125 His Ala Asp Asn Arg Glu Gly Leu Pro Asn Gln His Leu Glu Lys Lys 130 135 140 Tyr Phe Arg Glu Gly Asp Leu Gly Phe Gly Val Phe Asp Phe His Gly 145 150 155 160 Val Gln Val Gly Met Cys Leu Cys Asn Asp Arg Arg Trp Pro Glu Val 165 170 175 Tyr Arg Ser Leu Ala Leu Gln Gly Ala Glu Leu Val Val Leu Gly Tyr 180 185 190 Asn Thr Pro Asp Phe Val Pro Gly Trp Gln Glu Glu Pro His Ala Lys 195 200 205 Met Phe Thr His Leu Leu Ser Leu Gln Ala Gly Ala Tyr Gln Asn Ser 210 215 220 Val Phe Val Ala Ala Ala Gly Lys Ser Gly Phe Glu Asp Gly His His 225 230 235 240 Met Ile Gly Gly Ser Ala Val Ala Ala Pro Ser Gly Glu Ile Leu Ala 245 250 255 Lys Ala Ala Gly Glu Gly Asp Glu Val Val Val Val Lys Ala Asp Ile 260 265 270 Asp Met Gly Lys Pro Tyr Lys Glu Ser Val Phe Asp Phe Ala Ala His 275 280 285 Arg Arg Pro Asp Ala Tyr Gly Ile Ile Ala Glu Arg Lys Gly Arg Gly 290 295 300 Ala Pro Leu Pro Val Pro Phe Asn Val Asn Asp 305 310 315 3 458 PRT Arthrobacter aurescens 3 Met Phe Asp Val Ile Val Lys Asn Cys Arg Leu Val Ser Ser Asp Gly 1 5 10 15 Ile Thr Glu Ala Asp Ile Leu Val Lys Asp Gly Lys Val Ala Ala Ile 20 25 30 Ser Ala Asp Thr Ser Asp Val Glu Ala Ser Arg Thr Ile Asp Ala Gly 35 40 45 Gly Lys Phe Val Met Pro Gly Val Val Asp Glu His Val His Ile Ile 50 55 60 Asp Met Asp Leu Lys Asn Arg Tyr Gly Arg Phe Glu Leu Asp Ser Glu 65 70 75 80 Ser Ala Ala Val Gly Gly Ile Thr Thr Ile Ile Glu Met Pro Ile Thr 85 90 95 Phe Pro Pro Thr Thr Thr Leu Asp Ala Phe Leu Glu Lys Lys Lys Gln 100 105 110 Ala Gly Gln Arg Leu Lys Val Asp Phe Ala Leu Tyr Gly Gly Gly Val 115 120 125 Pro Gly Asn Leu Pro Glu Ile Arg Lys Met His Asp Ala Gly Ala Val 130 135 140 Gly Phe Lys Ser Met Met Ala Ala Ser Val Pro Gly Met Phe Asp Ala 145 150 155 160 Val Ser Asp Gly Glu Leu Phe Glu Ile Phe Gln Glu Ile Ala Ala Cys 165 170 175 Gly Ser Val Ile Val Val His Ala Glu Asn Glu Thr Ile Ile Gln Ala 180 185 190 Leu Gln Lys Gln Ile Lys Ala Ala Gly Gly Lys Asp Met Ala Ala Tyr 195 200 205 Glu Ala Ser Gln Pro Val Phe Gln Glu Asn Glu Ala Ile Gln Arg Ala 210 215 220 Leu Leu Leu Gln Lys Glu Ala Gly Cys Arg Leu Ile Val Leu His Val 225 230 235 240 Ser Asn Pro Asp Gly Val Glu Leu Ile His Gln Ala Gln Ser Glu Gly 245 250 255 Gln Asp Val His Cys Glu Ser Gly Pro Gln Tyr Leu Asn Ile Thr Thr 260 265 270 Asp Asp Ala Glu Arg Ile Gly Pro Tyr Met Lys Val Ala Pro Pro Val 275 280 285 Arg Ser Ala Glu Met Asn Ile Arg Leu Trp Glu Gln Leu Glu Asn Gly 290 295 300 Leu Ile Asp Thr Leu Gly Ser Asp His Gly Gly His Pro Val Glu Asp 305 310 315 320 Lys Glu Pro Gly Trp Lys Asp Val Trp Lys Ala Gly Asn Gly Ala Leu 325 330 335 Gly Leu Glu Thr Ser Leu Pro Met Met Leu Thr Asn Gly Val Asn Lys 340 345 350 Gly Arg Leu Ser Leu Glu Arg Leu Val Glu Val Met Cys Glu Lys Pro 355 360 365 Ala Lys Leu Phe Gly Ile Tyr Pro Gln Lys Gly Thr Leu Gln Val Gly 370 375 380 Ser Asp Ala Asp Leu Leu Ile Leu Asp Leu Asp Ile Asp Thr Lys Val 385 390 395 400 Asp Ala Ser Gln Phe Arg Ser Leu His Lys Tyr Ser Pro Phe Asp Gly 405 410 415 Met Pro Val Thr Gly Ala Pro Val Leu Thr Met Val Arg Gly Thr Val 420 425 430 Val Ala Glu Lys Gly Glu Val Leu Val Glu Gln Gly Phe Gly Gln Phe 435 440 445 Val Thr Arg Arg Asn Tyr Glu Ala Ser Lys 450 455 4 458 PRT Arthrobacter aurescens 4 Met Phe Asp Val Ile Val Lys Asn Cys Arg Leu Val Ser Ser Asp Gly 1 5 10 15 Ile Thr Glu Ala Asp Ile Leu Val Lys Asp Gly Lys Val Ala Ala Ile 20 25 30 Ser Ala Asp Thr Ser Asp Val Glu Ala Ser Arg Thr Ile Asp Ala Gly 35 40 45 Gly Lys Phe Val Met Pro Gly Val Val Asp Glu His Val His Ile Ile 50 55 60 Asp Met Asp Leu Lys Asn Arg Tyr Gly Arg Phe Glu Leu Asp Ser Glu 65 70 75 80 Ser Ala Ala Val Gly Gly Ile Thr Thr Ile Ile Glu Met Pro Ile Thr 85 90 95 Phe Pro Pro Thr Thr Thr Leu Asp Ala Phe Leu Glu Lys Lys Lys Gln 100 105 110 Ala Gly Gln Arg Leu Lys Val Asp Phe Ala Leu Tyr Gly Gly Gly Val 115 120 125 Pro Gly Asn Leu Pro Glu Ile Arg Lys Met His Asp Ala Gly Ala Val 130 135 140 Gly Phe Lys Ser Met Met Ala Ala Ser Val Pro Gly Met Phe Asp Ala 145 150 155 160 Val Ser Asp Gly Glu Leu Phe Glu Ile Phe Gln Glu Ile Ala Ala Cys 165 170 175 Gly Ser Val Ile Val Val His Ala Glu Asn Glu Thr Ile Ile Gln Ala 180 185 190 Leu Gln Lys Gln Ile Lys Ala Ala Gly Gly Lys Asp Met Ala Ala Tyr 195 200 205 Glu Ala Ser Gln Pro Val Phe Pro Glu Asn Glu Ala Ile Gln Arg Ala 210 215 220 Leu Leu Leu Tyr Lys Glu Ala Gly Cys Arg Leu Ile Val Leu His Val 225 230 235 240 Ser Asn Pro Asp Gly Val Glu Leu Ile His Gln Ala Gln Ser Glu Gly 245 250 255 Gln Asp Val His Cys Glu Ser Gly Pro Gln Tyr Leu Asn Ile Thr Thr 260 265 270 Asp Asp Ala Glu Arg Ile Gly Pro Tyr Met Lys Val Ala Pro Pro Val 275 280 285 Arg Ser Ala Glu Met Asn Ile Arg Leu Trp Glu Gln Leu Glu Asn Gly 290 295 300 Leu Ile Asp Thr Leu Gly Ser Asp His Gly Gly His Pro Val Glu Asp 305 310 315 320 Lys Glu Pro Gly Trp Lys Asp Val Trp Lys Ala Gly Asn Gly Ala Leu 325 330 335 Gly Leu Glu Thr Ser Leu Pro Met Met Leu Thr Asn Gly Val Asn Lys 340 345 350 Gly Arg Leu Ser Leu Glu Arg Leu Val Glu Val Met Cys Glu Lys Pro 355 360 365 Ala Lys Leu Phe Gly Ile Tyr Pro Gln Lys Gly Thr Leu Gln Val Gly 370 375 380 Ser Asp Ala Asp Leu Leu Ile Leu Asp Leu Asp Ile Asp Thr Lys Val 385 390 395 400 Asp Ala Ser Gln Phe Arg Ser Leu His Lys Tyr Ser Pro Phe Asp Gly 405 410 415 Met Pro Val Thr Gly Ala Pro Val Leu Thr Met Val Arg Gly Thr Val 420 425 430 Val Ala Glu Lys Gly Glu Val Leu Val Glu Gln Gly Phe Gly Gln Phe 435 440 445 Val Thr Arg Arg Asn Tyr Glu Ala Ser Lys 450 455 

1. A process for the production of an enantiomer-enriched α-substituted carboxylic acid comprising a) contacting a compound of formula (I) with a hydantoinase

wherein, X is O, S, or CH₂, and R is an enzyme-reactive organic residue, to form a product of formula (II)

wherein X and R are as defined above; and b) contacting the product of formula (ii) with a carbamoylase:
 2. The process according to claim 1, wherein R is selected from the group consisting of (C₁-C₈)-alkyl, (C₁-C₈)-alkoxy, (C₂-C₈)-alkoxyalkyl, (C₆-C₁₈)-aryl, (C₇-C₁₉)-aralkyl, (C₃-C₁₈)-heteroaryl, (C₄-C₁₉)-heteroaralkyl, (C₁-C₈)-alkyl-(C₆-C₁₈)-aryl, (C₁-C₈)-alkyl-(C₃-C₁₈)-heteroaryl, (C₃-C₈)-cycloalkyl, (C₁-C₈)-alkyl-(C₃-C₈)-cycloalkyl, (C₃-C₈)-cycloalkyl-(C₁-C₈)-alkyl, (C₁-C₈)-acyl, (C₁-C₈)-acyloxy, an α-residue of a natural amino acid, and an α-residue of an unnatural amino acid.
 3. The process according to claim 1, wherein the contacting in step a) is performed in the presence of a host organism expressing at least one enzyme selected from the group consisting of the hydantoinase and the carbamoylase.
 4. The process according to claim 1, further comprising contacting the compound of formula (I) with a racemase.
 5. The process according to claim 4, wherein the racemase is selected from the group consisting of a hydantoin racemase, a carbamoylamino acid racemase, and a N-acetylamino acid racemase.
 6. The process according to claim 4, wherein the contacting in step a) is performed in the presence of a host organism expressing at least one enzyme selected from the group consisting of the hydantoinase, the carbamoylase, and the racemase.
 7. The process according to claim 1, further comprising contacting the compound of formula (II) with a racemase.
 8. The process according to claim 7, wherein the racemase is selected from the group consisting of a hydantoin racemase, a carbamoylamino acid racemase, and a N-acetylamino acid racemase.
 9. The process according to claim 7, wherein the contacting in step a) is performed in the presence of a host organism expressing at least one enzyme selected from the group consisting of the hydantoinase, the carbamoylase, and the racemase.
 10. The process according to claim 1, wherein the hydantoinase is a Bacillus thermoglucosidasius hydantoinase.
 11. The process according to claim 1, wherein the carbamoylase is a Agrobacterium radiobacter carbamoylase.
 12. The process according to claim 1, which is performed in an enzyme membrane reactor.
 13. A process of producing a catalyst or a bioactive compound, comprising converting the compound obtained by the process of claim 1 into a catalyst or a bioactive compound.
 14. A process for the production of an enantiomer-enriched α-substituted carboxylic acid comprising contacting a carbamoylase with a compound of formula (II)

wherein X is O, S, or CH₂, and R is an enzyme-reactive organic residue.
 15. The process according to claim 14, wherein R is selected from the group consisting of (C₁-C₈)-alkyl, (C₁-C₈)-alkoxy, (C₂-C₈)-alkoxyalkyl, (C₆-C₁₈)-aryl, (C₇-C₁₉)-aralkyl, (C₃-C₁₈)-heteroaryl, (C₄-C₁₉)-heteroaralkyl, (C₁-C₈)-alkyl-(C₆-C₁₈)-aryl, (C₁-C₈)-alkyl-(C₃-C₁₈)-heteroaryl, (C₃-C₈)-cycloalkyl, (C₁-C₈)-alkyl-(C₃-C₈)-cycloalkyl, (C₃-C₈)-cycloalkyl-(C₁-C₈)-alkyl, (C₁-C₈)-acyl, (C₁-C₈)-acyloxy, an (α-residue of a natural amino acid, and an α-residue of an unnatural amino acid.
 16. The process according to claim 14, wherein the contacting in step a) is performed in the presence of a host organism expressing the carbamoylase.
 17. The process according to claim 14, further comprising contacting the compound of formula (II) with a racemase.
 18. The process according to claim 17, wherein the racemase is selected from the group consisting of a hydantoin racemase, a carbamoylamino acid racemase, and a N-acetylamino acid racemase.
 19. The process according to claim 17, wherein the contacting in step a) is performed in the presence of a host organism expressing at least one enzyme selected from the group consisting of the carbamoylase and the racemase.
 20. The process according to claim 17, wherein the carbamoylase is a Agrobacterium radiobacter carbamoylase.
 21. The process according to claim 17, which is performed in an enzyme membrane reactor.
 22. A process of producing a catalyst or a bioactive compound, comprising converting the compound obtained by the process of claim 17 into a catalyst or a bioactive compound. 